The present disclosure is directed to a soluble zinc polyphosphate complex for use in personal care compositions and methods of making the complex.
Zinc compounds are often used in oral care and personal care compositions. Many Zinc compounds possess hydrolysis chemistry and bacteria inhibiting qualities that render them suitable for oral care products. For instance, zinc is considered an anti-plaque agent. Compounds such as zinc citrate and zinc oxide have been added to toothpaste to prevent plaque buildup. Zinc salts can have other functions related to the body that make them desirable as active ingredients in other personal care products. For example, Zinc citrate as a trihydrate, Zn3 (C6H5O7) 2.3H2O which is a white odorless powder that is only slightly soluble in water, serves as an important antioxidant nutrient and is vital for protein synthesis, blood stability, normal tissue function and wound healing to name a few common uses by the body.
Polyphosphates are known in the art for use as, for example, chelants, in oral care compositions. In addition, polyphosphates such as diphosphate (also known as pyrophosphate) and triphosphate are known for use as anions in antiperspirants, as taught in WO 2013/013903, published on Jan. 31, 2013. Longer chain linear polyphosphates (more than 3 phosphate units) are susceptible to hydrolysis in aqueous compositions. Upon hydrolysis they are known to form orthophosphates which form insoluble zinc complexes.
Dentinal hypersensitivity (i.e. sensitivity) is a painful condition resulting from the movement of liquid in exposed dentin tubules from external stimuli such as pressure and temperature. On strategy to reduce and/or eliminate the pain resulting from exposed dentin tubules is to form insoluble precipitates in the tubules in order to physically plug the tubules. For instance, Stannous salts have been shown to treat dentinal hypersensitivity by depositing into tubules from neat solutions and from simple formulations, as described in U.S. Patent Application Publication No. 2009/0136432, the disclosure of which is hereby incorporated by reference in its entirety.
Antiperspirant substances often employ aluminum containing actives. These substances reduce the flow of sweat by forming a plug in the sweat duct. However, due to consumer concern about aluminum based antiperspirant products, Aluminum free antiperspirant actives are in demand.
The discovery of a novel zinc complex that can be used to treat dentinal hypersensitivity and/or that can act as an antiperspirant active would be a welcome addition to the art. In addition, it would be desirable to manipulate zinc salt structures in efforts to enhance efficacy and extend the applications of these compounds in oral care and personal care products.